Electric motor construction



1942- J. D. MINER, JR

ELECTRIC MOTOR CONSTRUCTION Filed April 17, 1940 John D. Miner, J1:

wnugzilh 5 22 4 W ATTORNEY P atcnted Nov. 3, 1942 new.

ELECTRIC MOTOR CONSTRUCTION John D. Miner, In, Lima, Ohio, minor toWestinghouse Electric & Manufacturing Company, East Pittsburgh, Put, acorporation of Pennsylvania Application April 17, 1940, Serial No.330,075

z'lClaims.

My invention relates to the manufacture of small motors of the universaltype, or other types in which the rotor-member is provided with acommutator.

The principal object of my invention is to provide a novel constructionfor such motors, so as to result in economical production in largequantities,

Motors of the type covered by this invention are usually provided with aprimary or field-core which is built up of a stack of laminations having pole-pieces integral with the magnetic yoke, as this form ofconstruction is the most economical for quantity-production. Motorshaving such a field-core construction must have their front and rearcasings or housing-brackets secured on, or by means of, through-bolts orstuds which must pass through stud-receiving perforations in the yokeportions of the field-core, ap-

proximately 90 electrical degrees from the center-line of thepole-pieces of the field-core, because the end-tumsof the field-winding,which surrounds the pole-pieces, would stand in the way so as to preventthe location of the studreceiving perforations in the pole-pieceportions of the field-core. At the same time, the brushholders of thesemotors ought to be placed in the same position, approximately 90electrical degrees from the center-line of the pole-pieces, as otherwisea. longer motor-construction would be required, as well as a special,less durable, and more costly, armature-winding, as well as prohibitinga flat-sided frame-shape such as may be required because ofspace-limitations.

In order that the above-mentioned studs may be in alinement with thebrushholders, it is necessary to provide an inwardly directed shoulderor lugs on the motor-frame, to provide an abutment for the front side orend of the fieldcore, and so that the front ends of these studs canterminate in said abutment, without having to extend the lugs all theway through to the front end of the front housing-bracket of the motor,thus leaving the space within the front housing-bracket free for themounting of the brushholders. The foregoing difficulties andconsiderations have resulted either in-the utilization of castings, forthe motor-housings, or special and unnatural, and hence costly,arrangements and locations of either the studs or the'brushholders, allof which results in increased costs, which are particularly to bedeplored in economical production in large quantities, where even smallcost-items mount up. because of the large numbers involved.-

An object of my present inventionis to provide a satisfactorydrawn-steel shell-construction, or other sheet-metal housing, for motorsof the above-mentioned type, thereby securing the known economies ofdrawn-steel construction without necessitating the abandonment of themost desirable positioning and spacing of the brushholders and studs.

A more specific object is to provide two sheetmetal housing-bracketshells which are generally similar in contour, one for the front end ofthe motor, to house the brushholders and commutator, and the Other forthe rear end of the motor, to house the ventilating fan, the front shellbeing provided with turned-in lugs for engaging the front ends of thestuds. In a preferred form of construction, the front shell is alsoprovided with a plurality of inwardly stabbed depressions for formingabutments for the front end of the field-core, in a plane spaced fromthe turned-in lugs, thus permitting a slight radius on the lugs, andalso permitting the field-core laminations to flare out, somewhat, inthe region of the turned-in lugs.

A further object of my invention is to utilize a shouldered stud whichpermits all of the internal parts of the stator-member to be firmlysecured within the front housing-shell, thus permitting a vastly fasterassembly than can be obtained when the internal parts are located bymeans of lugs, spacers or springs threaded on the stud,

besides providing a firm clamping of the fieldcore, which tends tominimize motor-noise. With this construction, the rear ends oi. thestuds,

which secure the rear housing-shell, may also be utilized as rearmounting-means for the motor, if desired.

A further object of my invention is to provide an improvedbearing-mounting means for supporting the spherical-type. self-alinin'gbearings which are usually provided on motors of this t p and at thesame time to provide additional clearance, at the front end of themotor, to make room for the brushholder connectors, while providing avery effective baiiie for the ventilating fan at the rear end of themotor.

With theforegoing and other objects in view, my invention consists in.the combinations, parts, structures and assembly-methods hereinafterdescribed and claimed, and illustrated in the accompanying drawingwherein:

Figure 1 is a top plan view of a motor manufactured in accordance withmy present invention;

Fig. 2 is a view of the same, partly in longitudinal section on the lineII--II of Fig. 1, and partly in elevation;

Fig. 3 is a front-end elevation of the motor; and

Fig. Us a rear-end elevation of the motor, with parts broken away toshow a section on the line IV-IV of Fig. 2. v

I have illustrated my invention as being embodied in a universalelectric motor comprising a two-pole field-core which is built up of astack of laminations 6 having pole-pieces I integral with the magneticyoke-portions 8. Each of the two pole-pieces I carries a field-winding9, as shown in Fig. 4. The motor is also provided with a rotor-member lhaving an armaturewinding ll terminating in a commutator II, which isdisposed on what is known as the front end of the motor. Therotor-member is mounted upon a shaft ll, so as to rotate within thepole-pieces I of the field-core B, so as to be separated therefrom by anair-gap M. The rear end of the rotor-member I0 is provided with aventilating fan I5.

The motor is provided with a housing in the form of two housing-bracketsor shells I8 and I! which are made of drawn-steel or other sheetmetalconstruction, and are preferably of the previously mentioned flat-sidedconstruction. These two housing-bracket shells are similar to eachother, in general outlines, having only slight differences in the mannerin which they are punched or perforated, to distinguish between thedifferent functions of the front shell l6 and the rear shell ll. Each ofthe shells I8 and I1 is of a general cup-shape, being provided with acylindrical portion I8 which more or less tightly embraces thefield-core 6, having a sliding fit over the yokeportions 8 thereof, andbeing usually spaced somewhat from the backs of the pole-pieces I of thefield-core, in order to provide clearance for the field-windings 9, asshown in Fig. 4. The cup-shaped shells l8 and I! also have endwalls I 9.

The front housing-bracket shell It has a plurality ofbrushholder-mounting perforations 2| (Fig. 3) in its front end-wall I9,said perforations 2i being adapted to receive the bent-over ears 2! of aclamp 23 which holds a brushholderassembly 24, illustrated as being of awell-known cartridge type. There are two brushholderassemblies 24, eachcarrying a brush 25 which bears upon the commutator l2, and each havinga brushholder-connector 26 which is utilized for making the properelectrical connections within the front shell it. These twobrushholder-assemblies 24 are disposed in the preferred place therefor,that is, in a. plane 90 electrical degrees from the center-line 21 (Fig.4) of the pole-pieces I, which, in a two-pole motor, as illustrated, isequivalent to saying that the brushholders are displaced by 90space-degrees from the field-pole center-line 21.

The cylindrical part l8 of the front shell I8 is also provided with twoturned-in lugs 30 which are disposed in spaced relation to the twobrushholder-assemblies 24, and in longitudinal alinement therewith.These two turned-in lugs 30 are each provided with a stud-receivingperforation II, which is preferably elongated in a radial direction, soas to make provision for manufacturing variations in the parts, so asnot to interfere with quick assembly. The lug-perforations Ii receivethe respective front ends of two studs or through-bolts 32 which extendthrough stud receiving perforations 33 in the yoke-portions 8 of thefield-core 6. In accordance with one feature of my invention, the studs32 are of a shouldered type, having a shoulder-forming enlargement 34intermediate their ends. The studshoulder 34 abuts up against the rearside of the field-core 6. The front end of each stud 82 passes throughthe perforation 3| in its corre sponding lug l0, and carries a nut 35which presses against the front side of the lug.

The rear end of each stud 32 extends through a suitable perforation 38(Fig. 4) which is provided in the end-wall is of the rear shell I], andis provided with a nut 31 which engages the rear side of said rear shellll. In this manner, the rear nuts 31 can be removed, and, if desired,also the rear shell II, without in the least disturbing the tightconnection between the fieldcore I and the front shell II. It will benoted that the assembly of the field-core 8 and the front shell l6 maybe made with the greatest ease, without the necessity for handling looseparts or spacers of any kind.

In the preferred construction of my improved motor, the front end orside of the field-core I does not abut up tight against the rear side ofthe turned-in lug 30, but is spaced therefrom by a certain distance,such as a, of an inch, being held in such spaced relation to the lug Illby means of a plurality of inwardly stabbed depressions 38 which arestabbed or pressed into the cylindrical portion ll of the front shellII, in order to provide core-receiving abutments in a plane which isslightly spaced, in a longitudinal or axial direction, from the plane ofthe two turned-in lugs 30. In this manner, I make allowance for theradius at the bend in the lugs N, where they are bent in from thecylindrical portion iii of the front shell i5, and I also make allowancefor a slight bulging or spreading action of the primary laminations 8,which frequently do not stay pressed together as tightly in the regionof the yoke-portions 8 as in the region of the polepieces I which areencompassed by the field-coil 8 and which are commonly riveted togetherby rivets 39 (Fig. 4).

Both of the housing-bracket shells l6 and I! have their end-walls [9provided with central bearing-receiving bulges 40, which are alike,except for the fact that the bulge 40 of the rear bracket-shell I1 isperforated, as indicated at H, to receive the shaft i3. Each of thebulges 40 has a tapering or inclined bearing-seating portion 42, forbearing against a rounded bearing 43 of the self-centering type. Each ofthe bearings 43 is further held in position by a lockingdisc 44 of afiat-spring type which is so bent as to provide a tapering or inclinedcentral bearingseating perforation l5.

Heretofore the flat-spring locking-disks H of the prior art have givensome trouble because they were tightly riveted to the inside surfaces ofthe end-wall l9, surrounding the bearing-receiving bulge 40, thedifficulty arising because the first rivet which is tightened into placedistorts the spring, or pushes it off-center, and holds it so tightlythat it cannot subsequently center itself when the other holding-rivetsare applied.

In accordance with my invention, I do not utilize rivets at all, forholding the flat-spring locking-disks 44 in operative relation to theirrespective bracket-shells l8 and 11, but I utilize a plurality ofeyelets 46, not as rivets for tightly clamping the parts together, butas links for loosely tying the parts together in spaced relationship, sothat the spring 44 is always free to center it- 2,300,957 self and topermit proper self-alinement of the.

rounded or spherical-type bearing 4}. The eyelets are a common form oftubular rivet or eyelet-member which is set or peened over by means ofautomatic eyeletting machines which set the eyelets or rivets to adefinite length.

Since I utilize machine-made drawn-steel shells. *and machine-made,preformed, fiat-spring lockbracket shell; housinga sheet-metal rearbracket shell: a plurality of brushholder-asseming disks 44, it is asimple matter to set the riveting or eyeleting machine (not shown) for apredetermined length of eyelet or rivet 46 so that it brings the springN to the desired tension, while leaving the spring free to move radiallywith respect to the surface of the end-wall I! of the housing-shells Itor IT, as the case may be, thus permitting the spring to centeritself-on the spherical bearing 43, while at the same time, the spring44 maintains its own proper position at right angles to the axis of themotor.

In the particular bearing-assembly'which is illustrated in the drawing,a space is provided around the bearing 43, and within thebearingreceiving bulge 4d and between said bulge and the bearingcentering-spring 4d, which is filled with oil-soaked felt washers 48 forthe purpose of storing additional lubricant for the bearing 43, topermit the latter to operate for as long a time as possible, without thenecessity for an oiling operation.

In accordance with my invention, the end-walls l9 of the twohousing-shells l6 and IT are each provided with a second bulge 59surrounding the bearing-receiving bulge 48, the second bulge 58 being ofan annular shape because of the presence of the first bulge 40. Thesecond annular bulge 50 has a radius sufficiently large to provideadditional clearance for the brushholder-connections mat the front endof the motor, and to provide an efiective fan-baffle at the rear end ofthe motor, as shown in Fig. 2. It is necessary that the second annularbaffle 50 at the rear end of the motor be provided with ventilatingperforations 5i, as shown in Fig. 4, and it is desirable also that thecorresponding annular bulge 50 at the front end of the motor be providedwith similar ventilating perforations 5 5 as shown in Fig. 3.

In this manner, I make the most effective utilization of the identicalshapes or outlines of the two housing-shells l6 and ii, whereby thefront bearing is properly spaced from the brushholders,

the housing-material surrounding the rear bearing is shaped to provide abaille for cooperating with the ventilating fan IS, the fronthousingshell l6 has an end-wall l9 which is utilized as a support forthe brushholder-clamp 23, and the rear housing-shell I1 is provided withan endwall 19 for providing an abutment for the rear nuts 31 of theassembly-studs 32.

While I have described and illustrated my invention in a single form ofembodiment, which is at present preferred, I wish it to be understoodthat many changes may be made by those skilled in the art, by way ofadditions, omissions and alterations, without departing from theessential spirit of my invention, particularly in its broader aspects. Idesire, therefore, that the appended claims shall be accorded thebroadest construction consistent with their language.

I claim as my invention:

1. An electric motor comprising: a field-core, said field-corecomprising a stack of laminations having pole-pieces integral with themagnetic yokes; field-windings on the pole-pieces of the field-core; arotor-member having a commutator at its front end; a sheet-metal fronthousingblies mounted within said front shell; saidbrushholder-assemblies comprising brushholder-connectors disposed-withinsaid front shell; said brushholder-assemblies further 0 om p ris i n gbrushes bearing upon said commutator; said front shell having aturned-in lug spaced back of at least one of the brushholder-assembliesin iongitudinal alinement therewith; said lug being provided with astud-receiving perforation; at least one of the yoke portions of thefield-core being provided with a longitudinally extending stud-receivingperforation disposed approximately ninety electrical degrees from acenter-line of the pole-pieces; means for holding the front shell inplace on the field-core, said means comprising a stud passing throughthe field-core perforation and the lug-perforation, and includingnutmeans for exerting a pressure between the front side of said lug andthe rear side of said fieldoore; and means for holding the rear shell inplace on the field-core 2. An electric motor comprising: a two-polefield-core, said field-core comprising a stack of laminations havingpole-pieces integral with the magnetic yoke; field-windings on thepole-pieces of the field-core; a rotor-member having a commutator at itsfront end; a sheet-metal front housing-bracket shell; a sheet-metal rearhous lug-bracket shell; two brushholder-assemblies; said front shellhaving a front end-wall having brushholder-mounting perforations, andeach brushholder-assembly comprisin a clamp having ears engaging throughsaid brushholder-mounting perforations in the front wall of'said frontshell; said brushholder-assemblies comprising brushholder-connectorsdisposed within said front shell; said brushholder-assemblies furthercomprising brushes bearing upon said commutator; said front shell havinga turned-in lug spaced back of each brushholder-assembly in longitudinalalinement therewith; each of the two turned-in lugs being provided witha stud- 7 receiving perforation; each of the two yoke portions of thefield-core being provided with a longitudinally extending stud-receivingperforation disposed approximately ninety degrees from the center-lineof the pole-pieces; and two studs, each passing through one of thefield-core perforations and through the perforation in thecorrespondingturned-in lug, and including nutmeans for exerting a pressure betweenthe front side of said lug and the rear side of said fieldcore; eachof-said studs comprising a rear extension; said rear shell having a rearend-wall having two perforations for receiving said rear extensions ofsaid studs, and nut-means on said rear extensions for exerting apressure on the rear side of the rear end-wall of said rear shell.

3. The invention as defined in claim characterized by the stud-receivingperforation in said turned-in lug being elongated in a radial direction.

4.. The invention as defined in claim 2, char acterized by thestud-receiving perforations in said turned-in lugs being elongated in aradial direction.

5. The invention as defined in claim 1. characterized by said frontshell having a plurality of inwardly stabbed depressions for formingabutments for the front end of the field-core in a plane spaced fromsaid turned-in lug.

6. The invention as defined in claim 2, characterized by said frontshell having a plurality abutments for the front end of the field-corein a plane spaced from said turned-in lugs.

7. The invention as defined in claim 1, characterized by said stud beinga shouldered stud having a shoulder-forming enlargement intermediate itsends, and nuts on the respective ends, said shoulder-forming enlargementabutting against the rear side of the field-core, and said nuts abuttingrespectively against the front side of the ing and the rear side of therear shell.

said field-core comprising a stack of laminations having pole-piecesintegral with the magnetic yokes; field-windings on the pole-pieces ofthe field-core; a rotor-member having a commutator at its front end; afront housing-bracket shell; a rear housing-bracket shell; a pluralityof bnishholder-assemblies mounted within said front shell; saidbrushholder-assemblies comprising brushholder-connectors disposed withinsaid front shell; said brushholder-assemblies further comprising brushesbearing upon said commutator; said front shell having an inwardlyprojecting lug spaced back of at least one of the brushholder-assembliesin longitudinal alinement therewith; said lug being provided with astudreceiving perforation; at least one of the yoke portions of thefield-core being provided with a longitudinally extending stud-receivingperforation disposed approximately ninety electrical degrees from acenter-line of the pole-pieces; means for holding the front shell inplace on the fieldcore, said means comprising a shouldered stud pessingthrough the field-core perforation and the lug-perforation, said studhaving a shoulderforming enlargement intermediate its ends, and nuts onthe respective ends, said shoulder-forming enlargement abutting againstthe rear side of the field-core, and said nuts abutting respectivelyagainst the front side of the lug and the rear side of the rear shell.

10. An electric motor comprising: a two-pole field-core, said field-corecomprising a stack of laminations having pole-pieces integral with themagnetic yoke; field-windings on the pole-pieces of the field-core; arotor-member having a commutator at its front end; a fronthousing-bracket shell; a rear housing-bracket shell; twobrushholder-assemblies mounted within said front shell; saidbrushholder-assemblies comprising brushholder-connectors disposed withinsaid front shell; said brushholder-assemblies further comprising brushesbearing upon said commutator; said front shell having an inwardlyprojecting shoulder-forming means spaced back of saidbrushholder-assemblies and having stud-receiving perforations inlongitudinal alinement with the respective brushholder-assemblies; eachof the two yoke portions of the field-core being provided with alongitudinally extending stud-receiving perforation disposedapproximately ninety degrees from the center-line of the pole-pieces:and two shouldered studs,- each passing through one of the field-coreperforations and through the corresponding perforation in saidshoulderof inwardly stabbed depressions for forming forming means, eachstud having a shoulderforming enlargement intermediate its ends, andnuts on its respective ends, said shoulder-forming enlargement abuttingagainst the rear side of the field-core, said nuts abutting respectivelyagainst the front side of said inwardly projecting shoulder-formingmeans and the rear side of said rear shell.

11. The invention as defined in claim 1, characterized by said front andrear shells being similar to each other in general outlines, and eachhaving an end-wall provided with a central bearing-receiving bulgehaving a tapering or inclined bearing-seating portion, the end-wall ofeach shell having a second annular bulge surrounding itsbearing-receiving bulge, and the rotor-member having a fan at its rearend, said second annular bulge having a radius sufficiently large toprovide additional clearance for the brushholder-connectors at the frontend of the motor and to provide a fan-baflle at the rear end of themotor, the annular bulge in at least the rear shell being perforated forair-circulation in conjunction with said fan.

12. The invention as defined in claim 2, characterized by said front andrear shells being similar to each other in general outlines, and eachhaving an end-wall provided with a central bearing-receiving bulgehaving a tapering or inclined bearing-seating portion, the end-wall ofeach shell having a second annular bulge surrounding itsbearing-receivirig bulge, and the rotor-member having a fan at its rearend, said second annular bulge having a radius sufficiently large toprovide additional clearance for the brushholderconnectors at the frontend of the motor and to provide a fan-baiile at the rear end of themotor, the annular bulge in at least the rear shell being perforated forair-circulation in conjunction with said fan.

13. The invention as defined in claim 1, characterized by said front andrear shells being similar to each other in general outlines, and eachhaving an end-wall provided with a central bearing-receiving bulge, abearing mounted within each of said bulges, the end-wall of each shellhaving a second annular bulge surrounding its bearing-receiving bulge,and the rotor-member having a fan at its rear end, said second annularbulge having a radius sufllciently large to provide additional clearancefor the brushholderconnectors at the front end of the motor and toprovide a fan-baiile at the rear end of the motor, the annular bulge inat least the rear shell being perforated for air-circulation inconjunction with said fan.

14. The invention as defined in claim 2, characterized by said front andrear shells being similar to each other in general outlines, and eachhaving an end-wall provided with a central bearing-receiving bulge, abearing mounted within each of said bulges, the end-wall of each shellhaving a second annular bulge surrounding its bearing-receiving bulge,and the rotor-member having a fan at its rear end, said second annularbulge having a radius sufficiently large to provide additional clearancefor the brushholderconnectors at the front end of the motor and toprovide a fan-baffle at the rear end of the m tor, said annular bulgesbeing perforated for air-circulation in conjunction with said fan.

15. The invention as defined in claim 1, characterized by said front andrear shells being similar to each other in general outlines, and eachhaving an end-wall provided with a central bearing-receiving bulgehaving a tapering or inclined bearing-seating portion, a roundedself-centering-type bearing mounted within each 'of said bulges, aflat-spring locking-disk disposed on the inside of each bulged end-walland having a tapering or inclined central bearing-seating perforationfor engaging its associated bearing, and holding-means for securing eachflat-spring locking-disk to its associated end-wall, the end-wail ofeach shell having a second annular bulgeisurrounding said holding-meansfor the flat-spring locking-disk, and the rotor-member having a fan atits rear end, said second annular bulge having a radius suflicientlylarge to rovide additional clearance for the brushhold r--connectors atthe front end of the motor and to pro vide a fan-baiiie at the rear endof the motor, the annular bulge in at least the rear shell beingperforated for air-circulation in conjunction with said fan.

id. The inventionas defined in claim 2, characterized by said front andrear shells being simi lar to each other in general outlines, and eachhaving an end-wall provided with a central bearing-receiving bulgehaving a tapering or inclined bearing-seating portion, a roundedself-centering-type bearing mounted within each of said bulges, afiat-spring locking-disk disposed on the inside of each bulged end-walland having a tapering or inclined central bearing-seating perforationfor engaging its associated bearing, and holding-means for securing eachfiat-spring locking-disk to its associated end-wall, the endwall of eachshell having a second annular bulge surrounding said holding-means forthe flat-- spring locking-disl:, and the rotor-member having a fan atits rear end, said second annular bulge having a radius sufficientlylarge to provide additional clearance for the brushholderconnectors atthe front end of the motor and to provide a fan-baffle at the rear endof the motor, the annular bulge in at least the rear shell beingperforated for air-circulation in conjunction with said fan.

17. The invention as defined in claim 1, characterized by said front andrear shells each hav ing an end-wall provided with a centralbearingreceiving bulge having a tapering or inclined bearing-seatingportion, a rounded self-centering-type bearing mounted within each ofsaid bulges, a flat-spring locking-disk disposed on the inside of eachbulged end-wall and having a tapering or inclined centralbearing-seating perforation for engaging its associated bearing, andmeans for holding eachfiat-spring locking-disk in a predetermined spacedrelation to the endwall of its associated shell.

18. The invention as defined in claim 2, characterized by said front andrear shells each having an end-wall provided with a centralbearingreceiving bulge having a tapering or inclined bearing-seatingportion, a rounded self-centering-type bearing mounted within each ofsaid bulges, a flat-spring locking-disk disposed on the inside of eachbulged end-wal1 and having a tapering or inclined centralbearing-seating perforation for engaging its associated bearing, andmeans for holding each flat-spring locking-disk in a predeterminedspaced relation to the endwall of its associated shell.

19. The invention as defined in claim 1, characterized by said front andrear shells each having an end-wall provided with a centralbearingreceiving bulge having a tapering or inclined bearing-seatingportion, a rounded self-center ing-type bearing mounted within each ofsaid bulges, a flat-spring locking-disk disposed on the inside of eachbulged end-wall and having a, tapering or inclined centralbearing-seating perforation for engaging its associated bearing, and aplurality of link-means for holding each flatspring locking-disk in apredetermined'spaced relation to the end-wall of its associated shell.

20. The invention as defined in claim 2, characterized by said front andrear shells each having an end-wall provided with a centralbearingreceiving bulge having a tapering or inclined bearing-seatingportion, a. rounded self-centering-type bearing mounted within each ofsaid bulges, a fiat-spring locking-disk disposed on the inside of eachbulged end-wall and having ta taperingor inclined centralbearing-seating per-- foration for engaging its associated bearing, anda plurality of link-means for holding each fiatspring locking-disk in apredetermined spaced relation to the end-wall of its associated shell.

21. The invention as defined in claim 1, characterized by said front andrear shells each having an end-wall provided with a centralbearingreceiving bulge having a tapering or inclined bearing-seatingportion, a rounded self-centering-type bearing mounted within each ofsaid bulges, a flat-spring locking-disk disposed on the inside of eachbulged end-wall and having a tapering or inclined centralbearing-seating per foration for engaging its associated bearing, and aplurality of eyelets for holding each fiat-spring locking disk in apredetermined spaced relation to the end-wall of its associated shell.

22. The invention as defined in. claim 2, characterized by said frontand rear shells each having an end-wall provided with a centralbearingreceiving bulge having a. tapering or inclined bearing-seatingportion, a rounded self-centering-type bearing mounted within each ofsaid bulges, a flat-spring locking-disk disposed on the inside of eachbulged end-wall and having a tapering or inclined centralbearing-seating perforation for engaging its associated bearing, and aplurality of eyelets for holding each flat-spring locking-disk in apredetermined spaced relation to the end-wall of its associated shell.

23. A motor having a stationary part having housing-means, a rotatablepart associated therewith, said rotatable part having a commutator atits front end and a fan at its rear end, said housing-means including aplurality of brushholder-means for supporting a plurality of brushesbearing upon said commutator in the front portion of said housing-means,said brushholdermeans including brushho'lder-connect'ors disposed withinthe front portion of said housing-means. said housing-means furtherincluding front and rear end-walls which are similar to each other ingeneral outlines, each end-wall being provided with a centralbearing-receiving bulge, a bearing mounted within each of said bulges,each end-wall having a second annular bulge surrounding itsbearing-receiving bulge, said second annular bulge having a radiussufllciently large to provide additional clearance for thebrushholde'r-connectors at the front end of the motor and to provide afan-baille at the rear end of the motor, the annular bulge in at leastthe rear endwall being perforated for air-circulation in conjunctionwith said fan.

24. A motor having a stationary part having housing-means, a rotatablepart associated therewith, and two rounded self-centering-type bearlugsfor the rotatable part, said rotatable part having a commutator at itsfront end and a fan at its rear end, said housing-means including aplurality of brushholder-means for supporting a plurality of brushesbearing upon said commutator in the front portion of said housingmeans,said brushholder-means including brushholder-connectors disposed withinthe front portion of said housing-means, said housing-means furtherincluding front and rear end-walls which are similar to each other ingeneral outlines, each end-wall being provided with a bearing-receivingbulge having a tapering or inclined bearingseatlng portion for receivingone of said bearings, a flat-spring locking-disk disposed on the insideof each bulged end-wall and having a tapering or inclined centralbearing-seating perforation for engaging its associated bearing, andholdingmeans for securing each flat-spring locking-disk to itsassociated end-wall, each end-wall having a second annular bulgesurrounding said holding-means for the fiat-spring locking-disk, saidsecond annular bulge having a radius sufficiently large to provideadditional clearance for the brushholder-connectors at thefront end ofthe motor and to provide a fan-baflie at the rear end of the motor, theannular bulge in at least the rear end-wall being perforated forair-circulation in conjunction with said fan.

25. A motor having a stationary part having housing-means, a rotatablepart associated therewith, and two rounded seli-centering-type bearingsfor the rotatable part, characterized by said housing-means includingtwo end-walls, each provided with a bearing-receiving bulge having atapering or inclined bearing-seating portion for receiving one oi saidbearings, a fiat-spring locking-disk disposed on the inside of eachbulged end-wall and having a tapering or inclined centralbearing-seating perforation for engaging its associated bearing, andmeans for holding each flat-spring locking-disk in a predeterminedspaced relation to its associated end-wall.

28. A motor having a stationary part having housing-means, a rotatablepart associated therewith, and two rounded self-centering-type bearingsfor the rotatable part, characterized by said housing-means includingtwo end-walls, each provided with a bearing-receiving bulge having atapering or inclined bearing-seating portion for receiving one of saidbearings, a flat-spring locking-disk disposed on the inside of eachbulged end-w and having a tapering or inclined central bearing-seatingperforation for engaging its associated bearing, and a plurality oflink-means for holding each flat-spring locking-disk in a predeterminedspaced relation to its associated end-wall.

27. A motor having a stationary part having housing-means, a rotatablepart associated therewith, and two rounded self-eentering-type bearingsfor the rotatable part, charcterized by said housing-means including twoend-walls, each provided with a bearing-receiving bulge having atapering or inclined bearing-seating portion for receiving one of saidbearings, a flat-spring locking-disk disposed on the inside of eachbulged end-wall and having a tapering or inclined centralbearing-seating perforation for engaging its associated bearing. and aplurality of eyelets for holding each fiat-spring locking-disk in apredetermined spaced relation to its associated end wall.

JOHN D. MINER, JR.

